"Substrates that are designed to mimic the extracellular matrix are useful tools for studying cellular processes. Recently, we showed how micropatterning single mesenchymal stem cells can be used to reveal geometric cues that guide lineage specification. Shapes that promote a contractile cytoskeleton promote osteogenesis while shapes that promote a less organized cytoskeleton promote adipogenesis. In a separate study we found that the density and affinity of an immobilized cell adhesion ligand influences lineage specification. Surfaces presenting the high affinity cyclic-RGD peptide guide MSCs to express elevated levels of osteogenic markers. In contrast, surfaces presenting the lower affinity linear-RGD peptide promote expression of markers associated with myogenesis at high density and neurogenesis at low density of ligand. In both of these studies, the control of integrin-mediated adhesion and actomyosin contractility were found to guide specific differentiation programs. In this talk, I will present our efforts in the design of model systems that vary physical and biochemical cues independently and together. These studies reveal a picture of the microenvironment where cell geometry, matrix mechanics, adhesion ligand presentation and paracrine signaling play a complementary role in guiding stem cell differentiation."